Adjustable idle air bypass



Oct. 16, 1962 w. 0. MANNING 3,053,725

ADJUSTABLE IDLE AIR BYPASS Filed April 30, 1958 3 Sheets-Sheet 1 INVENTOR. W/u/AM d/lmv/m'a E-E JJ 1962 w. o. MANNING 3; 5'8,i75 25 ADJUSTABLE IDLE AIR BYPASS Filed April so, 1958 s sheets-Sheena INVENTOR.

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ADJUSTABLE IDLE AIR BYPASS Filed April 30, 1958 3 Sheets-Sheet 5 l INVENTOR. I W/zL/AM 0. MANN/N6 3,058,725 ADJUSTABLE IDLE Am BYPASS William 0. Manning, Birmingham, Mich, assignor to Holley Carburetor Company, Van Dyke, Mich, a corporation of Michigan Filed Apr. 30, 1958, Ser. No. 731,956 9 Claims. (Cl. 261-23) This invention relates generally to fuel systems for internal combustion engines, and more specifically to means for supplying the air which is consumed by the engine during idle operation.

The usual carburetor of present design delivers idle air to the engine intake manifold by means of a partially open throttle valve. This method of maintaining idle engine operation has proved to be unsatisfactory, especially in those situations where the engine has not reached normal operating temperatures and the ambient temperature is low. When a carburetor of this type is idled in cold weather, the moisture content of the air drawn around the cracked throttle frequently condenses and freezes adjacent to and on the upper surface and edges of the throttle valve due to the cooling effect of the air flowing past the throttle. The ice which is so formed may clog the idle fuel ports and cause engine stalling.

Various designs of idle air bypass means have been proposed in order to eliminate this icing. Some of these have been non-adjustable, constantly-open conduits which supply a quantity of air posterior to the throttle valve,

while others have been of the adjustable variety. The constantly open, non-adjustable bypass systems are not generally desirable because of possible variations in engine characteristics.

The adjustable systems heretofore proposed have not been used because of the complexity of the design (especially in the multi-barrel-multi-stage carburetors) and the inaccessibility of the adjustment means. Almost all carburetors have air cleaners mounted thereon, and the air cleaners have become lower and larger in diameter as a result of increased air demands and automotive styling. This requires that the air cleaner be removed any time that adjustment of the idle air bypass is desired.

Accordingly, an object of this invention is to provide adjustable means for supplying idle air to the engine; and more specifically, an object of the invention is to provide easily accessible adjustable means for supplying idle air posterior to the carburetor throttle valve.

Other objects and advantages will become apparent when reference is made to the following specification and illustrations wherein:

FIGURE 1 is a top plan view of a carburetor embodying the invention and having its air cleaner removed.

FIGURE 2 is a side elevational view of the carburetor illustrated in FIGURE 1, with portions thereof in crosssection taken substantially on the plane of line 2-2 of FIGURE 1 and looking in the direction of the arrows.

FIGURE 3 is a view similar to FIGURE 2, except that the carburetor is fitted with an air cleaner and the section is taken substantially on the plane of line 3-3 of FIGURE 1, looking in the direction of the arrows.

FIGURE 4 is a bottom plan view of the carburetor shown by FIGURE 1, as viewed on the plane of line 44 of FIGURE 2 and looking in the direction of the arrows.

FIGURE 5 is a bottom plan view taken on the plane of line 55 of FIGURE 3 and looking in the direction of the arrows.

FIGURE 6 is a fragmentary cross-sectional view taken on the plane of line 6-6 of FIGURE 4 and looking in the direction of the arrows.

FIGURE 7 is an enlarged fragmentary cross-sectional view illustrating a modification of the invention.

rates Ftent FIGURE 8 is a portion of FIGURE 3 illustrating still another modification of the invention.

FIGURE 9 is the same as FIGURE 5, but illustrating the modification shown by FIGURE 8.

Referring now in greater detail to the illustrations, FIGURE 1 is a top plan view of a carburetor 10 having a body 12 with primary and secondary induction passages 14 and 16 respectively, extending therethrough. The air intake 18 mounted on the body 12 has a choke valve 20 therein adapted to control the flow of air therethrough. A choke control device indicated generally at 22 may be suitably connected to the choke valve in a manner well known in the art. In the particular carburetor illustrated, fuel metering blocks 24 and fuel bowls 26 are sequentially secured to the body 12 by any suitable means as by screws 28.

FIGURE 2 better illustrates the general arrangement within the carburetor. The primary induction passage is 'llustrated as containing a venturi 3G and a main fuel nozzle 32 disposed generally within the throat of the venturi. An idle fuel system is schematically illustrated by port 34 discharging posterior to throttle valve 36 and being in communication with the fuel bowl by means of suitable conduitry as by passage 38. The secondary induction passage 16 also has its separate fuel metering systems. All of the elements therein which are alike or similar to those within passages 14 are identified by like numerals. The secondary throttle valve 40, however, is different from the primary throttle in that it may be controlled either manually in accordance with primary throttle position or automatically in accordance with engine requirements.

The primary and secondary throttles 36 and 4% respectively, may be contained within a throttle body 42, which in turn may be suitably secured to the carburetor body 12. The entire carburetor assembly Ill may then be secured to the engine intake manifold 44.

FIGURE 3, a fragmentary crosssectional view of the carburetor 10, illustrates very generally an air cleaner 46 mounted thereon. The throttle body 12 is formed to provide a cavity 48 therein (see FIGURE 5) which is in communication with the incoming air supply by means of conduit 50. A conduit 52 (FIGURES 4 and 5) formed in throttle body 42 is also in communication with cavity 48 and serves to convey idle air to the induction passages 14 and 16 posterior to the throttle valves 36 and 40 through any suitable means such as the conduits 54, 56 and 58.

A projection 60, which may be formed as part of the carburetor body 12, may be formed to provide a passage adapted to slidably receive a metering valve 62. An internally threaded portion 64 of the projection 60 coacts with a threaded section of valve 62 in order to permit axial adjustments of valve 62. Any means, such as slot 66, may be provided to facilitate this adjustment of valve 62.

A second tubular member 68 may be secured to the projection 60, as by a threaded portion 70. The air cleaner 46 may then be biased downwardly against body 12 by virtue of some locking mechanism such as the wing-type nut '72 and the matting threaded section 74 on member 68.

With the above construction, the operation of the invention is readily apparent; that is, the idle speed of the engine may be varied by varying the amount of air passing through conduit 50, through chamber 48 past valve 62, through passages 52, 54 and 56 and into the induction passages 14 and I6 posterior to the throttle valves 36 and 40. It is evident that control of the amount of idle air can be accomplished by adjusting the valve 62 0 axially so that the desired amount of air will pass by it into conduit 52.

In the: above described embodiment of the invention ineluding-the use of a hollow air cleaner anchor stud, as illustrated by member 68 in FIGURE 3, adjustment of valve 62 is simply a matter of inserting a device such as a screwdriver through member 68 and turning the valve 62. The advantage and convenience of accomplishing this adjustment without having to remove the air cleaner and searching for an adjustment screw at the base of the carburetor is quite obvious.

Of course, it is not necessary that the metering of air be accomplished by the cooperative action of valve 62 and conduit 52. The structure may be modified, for example, as illustrated in FIGURE 7, wherein the actual metering is done entirely above chamber 48. In the modification, air enters through conduit 50a; it is then metered by valve 62a and subsequently passes into chamber 48'and conduit 52, from which it is distributed to the individual induction passages.

It should also be apparent that the invention may be employed in the same manner, whether idle air is bypassed into the primary induction passages, the secondary passages or both the primary and secondary passages. Both the preferred embodiment and the modification illustrated in FIGURE 7 are of one general type; that is, the air intake ports 50 and 50a are anterior to the venturi 30. FIGURE 8, however, illustrates a second modification wherein the air intake ports 50b are located posterior to the venturi 30. FIGURE 9 better illustrates the ports 50b communicating between the primary induction passages 14 and the chamber 48. The metering of air from chamber 48 is accomplished in the same way as illustrated by the preferred embodiment in FIGURES 3, 4 and 6.

This second modification .may be employed, for example, in those carburetors which require an indication of total air flow in order to properly meter the fuel there from. By allowing the idle air to pass the venturi 30 first and then be diverted past the throttle, the carburetor may take full advantage of the air flow. V

While but three embodiments of the invention are disclosed, other modifications are of'course possible Without exceeding the scope of the invention, as defined by the appended claims.

Whatl claim is:

1. An internal combustion engine carburetor, comprising a body having an aircleaner flange formed at one end thereof, at least one air induction passage extending through said body within the projected area of said flange, a throttle valve in said passage adapted when closed to cut off air flow through said passage to the extent, that said engine cannot operate for lack of air, a separate passage extending throughsaid body, said separate passage being' disposed generally parallel with respect to the axis of said flange and having an internally threaded portion,;a"conduit in said body communicating said separate passage with the end surface of said body enclosed by. said flange, said conduit having suflicient area to supply the air required to sustain-engine idle operation when said throttle valve is closed, a conduit between said separate. passage anda point. in said induction passage downstream of said throttle .valve therein, an externally threaded valve. member disposed inv saidseparate passage,. said .valve' member being. adjustable axially when rotated: to vary the amount of idle air by-passiug said throttle valve, and an aircleaner attaching member secured insaidseparate passage, said attaching: member being. hollow so: as to permit access therethrough of a suitable tool.frv rotating saidvalve member. a

2. Aninternal combustion engine carburetor, compris ing a body having anaircleaner flange formed at one end thereof, at least two air induction passages extendingthrough said body within the projected area of said flange; a throttle valve in each of said passagesadapted when closed to cut off air flow through said passage to the extent that said engine cannot operate for lack of air,.a

separate air passage extending through said body, said passage being disposed axially withrespect to said circular flange, a conduit in said body communicating said separate air passage with an end surface of said body enclosed by sm'd flan e, said conduit having suflicient area to supply the air required to sustain engine idle operation when said throttle valves are closed, and a branch conduit between said separate air passage anda point in at least one of said induction passages downstream. of said throttle valve therein.

3. An internal combustion engine carburetor, comprising a body having an aircleaner flange formed at one end thereof, at least two air induction passages extending through said body within the projected area of said flange, a'throttle valve in each of said passages adapted when closed to cut off air flow through said passage to the extent that said engine cannot operate for lack of air, a separate air passage extending through said body, said passage being disposed axially with respect to said circular flange and having an internally threaded portion, a conduit in said body communicating said separate air passage with an end surface of said body enclosed by said flange, said conduit having sufiicient area to supply'the air required to sustain engine idle operation when said throttle valves are closed, a branch conduit between said separate air passage and a point in at least one of said induction passages downstream of said throttle valve therein, a valve member disposed in said separate air passage, said valve member having external threads cooperating with said internally threaded portion so as to enable axial adjustment thereof in said separate air passage by rotation of said valve member, said valve member and said separate air passage being formed so that axial adjustment of said valve member varies the amounts of idle air supplied to said engine through said branch conduits.

4. An internal combustion engine carbureton comprising a body having an aircleaner flange formed'at one end thereof, at least two air induction passages extending through said body within the projected area of said flange, a throttle valve in each of said passages adapted when closed to cut ofi air flow through said passage to the extent that said engine cannot operate for lack of air, a separate air passage extending through said body, said passage being disposed' axially with respect to said circular flange and having an internally threaded portion, a conduit in said body communicating said separate air passage with an end surface of said body enclosed by said flange, said conduit. having suflicient area to supply the air required to sustain engine idleoperation when said throttle valves are closed, a branch conduit between said separate air passage and a point in at least one of said induction passages downstream ofv said throttle valve therein, a valve member disposed in said separate air passage, said valve member having external threads cooperating with said internally threaded portion so as to enable axial adjustment thereof in said. separate air passage by rotation of said valve member, said valve member and said conduit being formed so that axial adjustment of said valve member varies the amounts of idle air supplied to said engine through said branch conduits.

5. An internal combustion engine carburetor, comprising a body having an aircleaner flange formed at one end thereof, at least two air induction passages extending through said body within the projected area of said flange. a throttle valve in each of said passages adapted when closed to cut off air flow through said passage to the extent that said engine cannot operate for lack of air, a separate passage extending through said body, said passage being disposed axially with respect to said circular flange and having an internally threaded portion, a conduit in said body communicating said separate passage with an end surface of said body enclosed by said flange, said conduit having suflicient area to supply the air required to sustain engine idle operation when said throttle valves are closed, a branch conduit between said separate passage and a point in at least one of said induction passages downstream of said throttle valve therein, a valve member disposed in said separate passage, said valve member having external threads cooperating with said internally threaded portion so as to enable axial adjustment thereof in said separate passage by rotation of said valve member, said valve member and said separate passage being formed so that axial adjustment of said valve member varies the amounts of idle air supplied to said engine through said branch conduits, an aircleaner attaching member secured in said separate passage, said attaching member having an opening aligned with said separate passage so as to permit access therethrough of a suitable tool for rotating said valve member.

6. An internal combustion engine carburetor, comprising a body having at least two air induction passages extending therethrough for supplying combustion air to said engine, a throttle valve in each of said induction passages adapted when closed to cut ofl air flow through said passages to the extent that engine idle operation cannot be sustained, an aircleaner mounting flange formed at one end of said body and encircling said induction passages, a separate passage extending through said body between said induction passages, said separate passage being disposed axially with respect to said flange and having a threaded portion, an aircleaner mounting stud retained in said separate passage at the flange end of said body, said stud being hollow throughout its length to permit access therethrough to said separate passage, a conduit formed in said body, said conduit extending from the end of said body within said flange and communicating with said separate passage, a branch conduit communicating between said separate passage and at least one of said induction passages at a point downstream of said throttle valve therein, said conduits and said separate passage having suflicient cross-sectoinal area to flow the air required to maintain engine idle operation when said throttle valves are closed, and a valve member disposed in said separate passage and adjustable through said hollow stud when said aircleaner is in place on said flange, said valve member being constructed and arranged with respect to said conduits that adjustment thereof varies the amount of idle air supplied to said engine.

7. An internal combustion engine carburetor, comprising a body having at least two air induction passages extending therethrough for supplying combustion air to said engine, a throttle valve in each of said induction passages adapted when closed to cut ofi air flow through said passages to the extent that engine idle operation cannot be sustained, an aircleaner mounting flange formed at one end of said body and encircling said induction passages, a separate passage extending through said body between said induction passages, said separate passage being disposed axially with respect to said flange and having a threaded portion and a valve seat formed therein, an aircleaner mounting stud retained in said separate passage at the flange end of said body, said stud being hollow throughout its length to permit access therethrough to said separate passage, a conduit formed in said body, said conduit extending from the end of said body within said flange and communicating with said separate passage,

a branch conduit communicating between said separate passage and at least one of said induction passages at a point downstream of said throttle valve therein, said conduits and said separate passage being of suflicient crosssectional area to maintain engine idle operation when said throttle valves are closed, and a valve member disposed in said separate passage and adjustable through said hollow stud when said aircleaner is in place on said flange, said valve member being constructed and arranged with respect to said seat that adjustment thereof varies the amounts of idle air supplied to said engine.

8. An internal combustion engine carburetor, comprising a body having an aircleaner flange formed at one end thereof, at least one air induction passage extending through said body within the projected area of said flange, a throttle valve in said passage adapted when closed to cut off airflow through said passage to the extent that said engine cannot operate for lack of air, a separate passage extending through said body, a conduit in said body communicating said separate passage with the end surface of said body enclosed by said flange, said conduit having sufficient area to supply the air required to sustain engine idle operation when said throttle valve is closed, a conduit between said separate passage and a point in said induction passage downstream of said throttle valve, a valve member disposed in said separate passage, said valve member being adjustable to vary the amount of idle air bypassing said throttle valve, and an aircleaner attaching member secured to said body at said separate passage, said attaching member having a passage formed therein to permit access therethrough to said valve.

9. An internal combustion engine carburetor, comprising a body having an aircleaner flange formed at one end thereof, at least one air induction passage extending through said body within the projected area of said flange, a throttle valve in said passage adapted when closed to cut off airflow through said passage to the extent that said engine cannot operate for lack of air, a separate passage extending through said body, said separate passage communicating with a point in said induction passage downstream of said throttle valve, a conduit in said body communicating said separate passage with the end surface of said body enclosed by said flange, said conduit having suflicient area to supply the air required to sustain engine idle operation when said throttle valve is closed, a valve member disposed in said separate passage, said valve member being adjustable to vary the amount of idle air bypassing said throttle valve, and an aircleaner attaching member secured to said body at said separate passage, said attaching member having a passage formed therein to permit access therethrough and through said separate passage to said valve.

References Cited in the file of this patent UNITED STATES PATENTS 1,956,992 Mallory May 1, 1934 2,060,747 Rayfield Nov. 10, 1936 2,296,697 Ball Sept. 22, 1942 2,618,474 Agar Nov. 18, 1952 2,757,914 Ball Aug. 7, 1956 

